The EL150EX Liquid Level Swichgage instrument is an explosion proof combination liquid level gauge and low limit switch. When properly installed and maintained, the float operates the pointer which, in turn, both indicates level during normal operation, and closes a switching circuit if the level falls to the low-limit set point. The primary use of the EL150EX is for engine cooling systems, surge or expansion tanks, condenser radiator or vapor phase systems, pressurized or atmospheric systems.